Child seats used in cars and other vehicles typically comprise a cushioned seat shell and an adjustable restraint harness for restraining and securing the child in the seat shell. The restraint harness typically comprises a first, a second and a third web strap forming a “Y” when the restraint harness is properly used. The first and second straps are when used arranged over a child's shoulders while the third strap is arranged between the child's legs. The first and second straps are generally releasably connected to a buckle to which also the third strap is attached. The other end of the third strap is generally fixedly secured to the seat. The first and second straps normally pass through slots provided in the back portion of the seat shell and are on the backside of the back portion fastened to a bracket or sewed together.
It is important to allow for adjustment of the length of the restraint harness in order to comfortably secure children of different sizes or even the same child with or without heavy clothes. It is well known in the art that this may be accomplished in many ways.
Generally, a fourth strap is attached to said bracket on the backside of the seat's back portion. Alternatively, the fourth strap may be sewed on the first and seconds straps. This fourth strap is arranged to extend forwardly through a slot formed in the seat portion. To allow for tightening or loosening of this strap, the strap normally extends through an adjuster device. Such an adjuster device is often referred to as a central (web or strap) adjuster. Loosening or tightening of the fourth strap via operation of the strap adjuster results in loosening or tightening of the harness, more specifically loosening or tightening of the first and second straps (shoulder straps).
Alternatively, the third strap may be pulled through an opening in the bottom of the seat shell and threaded under the seat portion to reach the adjuster device. When the third strap is tightened via operation of the adjuster device, the buckle is pulled downwardly and as a consequence thereof the first and the second straps are tightened. This configuration is rarely used nowadays.
This type of adjusters is normally configured to, when in its closed, fastening position, engage, stop or impede movement of the strap in one direction while still allowing the strap to be tightened by pulling the free strap end in the opposite direction. An important aspect of the adjuster is to impede the strap from slipping back through the adjuster device unless the adjuster is released.
There are many known types of web adjusters. A commonly used type is the cam adjuster, in which a rotating cam with a ridged surface compresses the web strap against an opposing surface to thereby secure the strap in a fastening position. An example of a cam type adjuster is illustrated in U.S. Pat. No. 4,679,852. A drawback with the cam type adjuster is that the cam ridges, which grab into the web while securing it, causes wear and tear of the web.
Another type of adjuster is illustrated in US 2008/0054691 (Glover). This web adjuster assembly uses a second plate hingedly biased against a first plate with a strap laced through an opening on the first plate and through openings on the second plate such that when the two plates are substantially resting against one another, friction prevents the strap from being pulled back through the web adjuster assembly.
While both cam adjusters and other adjusters are known in the art, there is still a need for an improved adjuster which fulfills the above mentioned requirements.